EP2421048A1 - Transistor à film mince et son procédé de fabrication - Google Patents

Transistor à film mince et son procédé de fabrication Download PDF

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Publication number
EP2421048A1
EP2421048A1 EP10764534A EP10764534A EP2421048A1 EP 2421048 A1 EP2421048 A1 EP 2421048A1 EP 10764534 A EP10764534 A EP 10764534A EP 10764534 A EP10764534 A EP 10764534A EP 2421048 A1 EP2421048 A1 EP 2421048A1
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Prior art keywords
film
channel layer
thin film
film transistor
oxide film
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EP10764534A
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German (de)
English (en)
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EP2421048A4 (fr
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Osamu Shiino
Kaoru Sugie
Yoshinori Iwabuchi
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Bridgestone Corp
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Bridgestone Corp
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Priority claimed from JP2009101020A external-priority patent/JP2010251606A/ja
Priority claimed from JP2009101005A external-priority patent/JP2010251604A/ja
Priority claimed from JP2009130965A external-priority patent/JP2010278336A/ja
Application filed by Bridgestone Corp filed Critical Bridgestone Corp
Publication of EP2421048A1 publication Critical patent/EP2421048A1/fr
Publication of EP2421048A4 publication Critical patent/EP2421048A4/fr
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/7869—Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/08—Oxides
    • C23C14/086—Oxides of zinc, germanium, cadmium, indium, tin, thallium or bismuth
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34—Sputtering
    • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
    • C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
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    • H01L21/02365—Forming inorganic semiconducting materials on a substrate
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    • H01L21/02565—Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
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    • H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
    • H01L29/66409—Unipolar field-effect transistors
    • H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
    • H01L29/66742—Thin film unipolar transistors
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/66007—Multistep manufacturing processes
    • H01L29/66969—Multistep manufacturing processes of devices having semiconductor bodies not comprising group 14 or group 13/15 materials
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/7869—Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
    • H01L29/78693—Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate the semiconducting oxide being amorphous
    • H—ELECTRICITY
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    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/78696—Thin film transistors, i.e. transistors with a channel being at least partly a thin film characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel

Definitions

  • the present invention relates to a method for manufacturing a thin film transistor wherein a channel layer or a part thereof and, further, electrodes such as a source electrode, a drain electrode, and a gate electrode are formed of an indium-containing metal oxide film.
  • amorphous silicon (a-Si) has been often used in thin film transistors, and, therefore, a high-temperature process and an expensive film forming apparatus are needed.
  • the need for a high-temperature process makes it difficult to fabricate a device (element) onto a polymer substrate or the like.
  • oxide semiconductors particularly transparent oxide semiconductors
  • IGZO In-Ga-Zn-O oxide semiconductor
  • a-Si Non-patent Document 1: Nature, 2004, Vol. 432, p. 488
  • utilization thereof as a driving backside board for a liquid crystal display, an organic EL display or the like has been attempted.
  • IGZO is superior to the above-mentioned a-Si as semiconductor material for TFT devices.
  • the mobility, which is the most important characteristic of TFT device, of IGZO exceeds 1 cm 2 /Vsec and is above the mobility value of 0.1 to 1 cm 2 /Vsec obtainable with a-Si.
  • the other point is that while the a-Si forming process temperature is not lower than 300°C, an IGZO film having the above-mentioned favorable mobility can be obtained even through a non-heating process.
  • IGZO is highly advantageous in that it has a high tendency to maintain an amorphous state, so that stable characteristics can be easily obtained and that it is excellent in film flexibility.
  • IGZO thus has very high performances, however, IGZO is disadvantageous in that it contains harmful Ga, and it needs a very precise control of oxygen content in the film; in other words, IGZO has difficulties in handleability and in control of film formation. Besides, IGZO is disadvantageous in that its composition is complicated because it contains three kinds of metallic elements, and, further, in that its novel introduction into a production line is difficult because it is a material which has not hitherto been handled.
  • In-W-O as a semiconductor material which can be comparatively easily formed (shaped) by a non-heating sputtering film-forming method and which has both a high mobility in excess of 1 cm 2 /Vsec and amorphousness
  • Patent Document 1 JP-A 2008-192721 .
  • this In-W-O film has three great merits, namely, (1) that it has a high mobility in excess of 1 cm 2 /Vsec, (2) that it can be formed by a non-heating sputtering film-forming method, and (3) that it has amorphousness; thus, the In-W-O film is very useful as a semiconductor film for thin film transistors.
  • the characteristics required of semiconductor parts in recent years are extremely high, and it is desired to develop a semiconductor film having a further enhanced mobility. Development of such a semiconductor film ensures that characteristics of a TFT (thin film transistor) can be further enhanced, resulting in that the performance of the device to which the transistor film is applied can also be further enhanced. This simultaneously means that the robustness as a material is expanded and the ease in using the material is enhanced.
  • TFT thin film transistor
  • CMOS complementary metal-oxide-semiconductor
  • solar cells bipolar operations, namely, not only an n-type operation but also a p-type operation are demanded.
  • Non-patent Document 2 Applied Physics Letters 90, 262104 (2007 ) discloses an n-type and p-type bipolar transistor based on an organic-inorganic semiconductor structure.
  • pentacene is used as an organic semiconductor material showing p-type characteristics
  • IZO is used as an oxide semiconductor showing n-type characteristics.
  • Patent Document 1 discloses a thin film transistor wherein conductivity of a film can be controlled by forming a channel layer from a film of an indium-containing metal oxide such as indium oxide (In 2 O 3 ), tin-doped indium oxide (ITO), or, further, titanium-or tungsten-doped indium oxide (InTiO x , InWO x ), etc.
  • an indium-containing metal oxide such as indium oxide (In 2 O 3 ), tin-doped indium oxide (ITO), or, further, titanium-or tungsten-doped indium oxide (InTiO x , InWO x ), etc.
  • the inorganic semiconductor material for the bipolar transistor of the organic-inorganic semiconductor structure described in Non-patent Document 2 is formed not of IZO but of the material described in Patent Document 1.
  • the approach in which the metal oxide film as an inorganic semiconductor is simply formed of the material described in Patent Document 1 results in that the characteristic properties of the metal oxide film would be changed when the organic semiconductor is disposed on the metal oxide film.
  • Patent Document 1 discloses in any way a bipolar transistor of an organic-inorganic semiconductor structure which has sufficiently high performance and high reliability while maintaining good semiconductor characteristics of characteristics of an oxide semiconductor, in the case where the oxide semiconductor and an organic semiconductor are stacked on each other as above-mentioned.
  • the flow rate of oxygen introduced during film formation has a very great influence on the characteristics of the film formed, so that very precise control of the flow rate of oxygen introduced is needed.
  • PEM control plasma emission monitor control
  • the states of the interfaces between the semiconductor film surface (channel layer) formed of the above-mentioned In-W-O film and source/drain electrodes and the interface between the semiconductor film surface and the gate insulating film are liable to be instable, so that it is difficult for the characteristics of the TFT device to become stable.
  • the above-mentioned In-W-O film is liable to have many defects generated therein, so that it is difficult to obtain stable TFT device characteristics.
  • the transfer characteristic of the TFT device is largely shifted due to bias stress. Therefore, in order to apply the TFT device using the film of the indium-containing metal oxide such as In-W-O as above-mentioned to an actual electronic device, it is indispensable to maintain more stable characteristics, and development of a measure therefor is desired.
  • the present invention has been made in consideration of the above-mentioned circumstances. Accordingly, it is a first object of the present invention to develop a semiconductor film which can be formed by a non-heating sputtering film-forming method, has good amorphousness and, further, has a high mobility, and thereby to provide a thin film transistor having higher performance. In addition, it is a second object of the present invention to construct a bipolar thin film transistor capable of good n-type and p-type bipolar operations, the bipolar thin film transistor having high performance and high reliability while maintaining good semiconductor characteristics of an oxide semiconductor, in the case where a channel layer is formed by stacking the oxide semiconductor and an organic semiconductor.
  • the present inventors made earnest investigations. As a result of the investigations, the present inventors found out that metal oxide films of indium oxides (In-W-Zn-O, In-W-Sn-O, In-W-Sn-Zn-O) obtained by further doping tungsten-doped indium oxide (In-W-O) with zinc and/or tin exhibit high mobility in large excess of that of conventional In-W-O, the films can be formed by a favorable non-heating process, and the films have good amorphousness. The present inventors have also found that when a device including a channel layer is formed by use of the metal oxide film, it is possible to comparatively easily fabricate a thin film transistor having high performance.
  • the present invention provides, as a first-named invention, a thin film transistor including elements including three electrodes of a source electrode, a drain electrode and a gate electrode, as well as a channel layer and a gate insulating film, wherein the channel layer is formed of an indium oxide film doped with tungsten and zinc and/or tin.
  • the second object is attained by forming the channel layer from a stack including an organic material film, and a metal oxide film which contains indium doped with at least one of tungsten, tin and titanium and which has an electrical resistivity that is preliminarily controlled.
  • the present invention provides, as a second-named invention, a bipolar thin film transistor including elements including three electrodes of a source electrode, a drain electrode and a gate electrode, as well as a channel layer and a gate insulating film, wherein the channel layer is a stack including an organic material film, and a metal oxide film which contains indium doped with at least one of tungsten, tin and titanium and which has an electrical resistivity that is preliminarily controlled.
  • a metal oxide film which has an electrical resistivity that is preliminarily controlled means an oxide film of which conductivity is preliminarily controlled before stacking, taking into account the characteristics of the oxide film, so as to maintain good semiconductor characteristics of characteristics of an oxide semiconductor, in the case where a channel layer is formed by stacking the oxide semiconductor and an organic semiconductor.
  • the organic material film is preferably F8T2, P3HT, pentacene, tetrabenzoporphyrin.
  • the channel layer preferably has the metal oxide and the organic material film stacked in this order from the side of the gate electrode. Besides, the source electrode and the drain electrode are mounted in contact with the organic material film. Incidentally, to make contact with the organic material film means that, when the channel is formed by stacking the metal oxide layer and the organic material layer, the source electrode and the drain electrode are provided on the organic material layer.
  • the amount of tungsten contained in the metal oxide film is preferably not less than 0.5 wt% and less than 15 wt%.
  • the electrical resistivity of the metal oxide film is preferably 10 -1 to 10 4 ⁇ cm.
  • the investigations includes an investigation of the case where sputtering using an indium-containing target is conducted in an oxygen gas-containing atmosphere, whereby an indium-containing metal oxide film is formed in a predetermined pattern on a substrate, and one or more elements including a channel layer or a part of the channel layer in a TFT device are formed from the indium-containing metal oxide film, to thereby manufacture a thin film transistor.
  • the present invention provides, as a third-named invention, a method for manufacturing a thin film transistor, including forming on a substrate an indium-containing metal oxide film in a predetermined pattern by sputtering conducted using an indium-containing target in an oxygen gas-containing atmosphere so that one or more elements including at least a channel layer or a part of the channel layer, of elements of the channel layer, a source electrode, a drain electrode and a gate electrode, are formed from the indium-containing metal oxide film, wherein the metal oxide film is formed by conducting the sputtering without heating the substrate, then the elements of the channel layer, the source electrode, the drain electrode and the gate electrode are formed over the substrate, and thereafter a heat treatment is conducted.
  • the present inventors advanced the investigations further.
  • the indium-containing metal oxide film it is preferable to form an indium oxide film doped with one or more of tin, titanium, tungsten and zinc by using a sintered body of indium oxide doped with one or more of tin, titanium, tungsten and zinc, as the indium-containing target.
  • TFT characteristics such as threshold voltage and mobility can be easily controlled by controlling the amount of W and the amount of Zn.
  • the present invention provides, as preferred embodiments of the third-named invention, the inventions of the following paragraphs (1) to (5).
  • the channel layer is formed from the semiconductor film having attained a higher mobility while maintaining the characteristic features of being formable by a non-heating sputtering film-forming method and having both high mobility and amorphousness, whereby a high-performance thin film transistor can be obtained with high productivity.
  • the metal oxide film includes indium doped with at least one of tungsten, tin, and titanium and has an electrical resistivity that is preliminarily controlled.
  • This configuration ensures that, even in the case where the organic material film is stacked on the metal oxide film, it is possible to provide a bipolar thin film transistor capable of n-type and p-type bipolar operations, the transistor having high performance and high reliability while maintaining good semiconductor characteristics of characteristics of the metal oxide film. Further, it is possible to provide a bipolar thin film transistor which is capable of n-type and p-type bipolar operations and which is low in cost and high in thermal stability.
  • the third-named invention it is possible to obtain an indium-containing metal oxide film having stable characteristics, through comparatively easy control, while maintaining the characteristic features of being formable by a non-heating sputtering film-forming method and having both high mobility and amorphousness, whereby a TFT device having stable characteristics can be obtained.
  • the thin film transistor according to the first-named invention is one in which a channel layer is formed of an indium oxide film doped with tungsten and zinc and/or tin, and which can be exemplified by a TFT device of the structure shown in FIG. 1 , for example.
  • the thin film transistor of FIG. 1 is one in which the channel layer 3 is formed on an Si substrate 1 (gate electrode) formed on its surface with a thermal oxide film (SiO 2 ) as a gate insulating film 2, and, further, a source electrode 4 and a drain electrode 5 are formed on the channel layer 3.
  • the channel layer 3 is formed from an indium-containing metal oxide film.
  • symbol 6 in FIG. 1 denotes a silver paste 6 for conduction with the Si substrate (gate electrode).
  • the metal oxide film for forming the channel layer 3 is, as above-mentioned, an indium oxide film doped with tungsten and zinc and/or tin; in other words, In-W-Zn-O, In-W-Sn-O or In-W-Sn-Zn-O is used.
  • Each of these indium oxide films can form a transparent conductive film, so that a transparent thin film transistor can be fabricated.
  • these have a tendency to retain amorphousness and are excellent in thermal stability and film flatness properties. Further, by controlling the W content, Zn content and Sn content of a target in forming these metal oxide films by sputtering, it is possible to easily control the TFT characteristics.
  • the channel layer 3 has an electrical resistivity which is normally controlled to 10 -1 to 10 6 ⁇ cm, particularly 1 to 10 5 ⁇ cm.
  • the above-mentioned Tn--W-Zn-O, In-W-Sn-O and In-W-Sn-Zn-O each permit its electrical resistivity to be comparatively easily controlled by controlling the degree of oxygen deficiency at the time of forming the film thereof.
  • the film-forming method in the case of forming the channel layer 3 from the In-W-Zn-O film, the In-W-Sn-O film or the In-M-Sn-Zn-O film there can be used physical vapor deposition methods such as a DC reactive sputtering method, an RF sputtering method, and a pulse laser evaporation method. Particularly, a sputtering method conducted using an indium-containing target in an oxygen gas-containing atmosphere is adopted preferably.
  • the oxygen deficiency of the In-W-Zn-O film, the In-W-Sn-O film or the In-W-Sn-Zn-O film can be controlled, whereby the electrical resistivity of the film can be controlled to the above-mentioned resistivity that is suitable for the channel layer 3.
  • an InWZn metal target and an In-W-Zn-O ceramic target can be used in the case of forming the In-W-Zn-O film
  • an InWSn metal target and an In-W-Sn-O ceramic target can be used in the case of forming the In-W-Sn-O film
  • an InWSnZn metal target and the In-W-Sn-Zn-O ceramic target can be used in the case of forming the In-W-Sn-Zn-O film, respectively.
  • the metal oxide film indium-containing metal oxide film by the DC reactive sputtering method or the RF sputtering method, in the present invention it is unnecessary to heat the substrate, and the metal oxide film can be favorably formed by conducting the sputtering at normal temperature.
  • productivity can be enhanced by applying a dual cathode sputtering method in which a pulsed voltage is applied alternately to a plurality of cathodes to thereby form the metal oxide film at high speed.
  • a feedback system based on PEM (Plasma Emission Monitor) control in which the amount of oxygen introduced is controlled on a real-time basis by measuring the ion concentrations in the plasma may be used, whereby stable control of the composition and the oxygen content of the thin film can be achieved.
  • PEM Pulsma Emission Monitor
  • the source electrode 4 and the drain electrode 5 there can be used known materials, for example, transparent electrode materials such as In 2 O 3 , ITO, FTO, In-Ti-O film, In-W-O film, etc., and, if transparency is not demanded, such metallic materials as Au, Pt, Ti, Al, etc., and various conductive polymer materials.
  • transparent electrode materials such as In 2 O 3 , ITO, FTO, In-Ti-O film, In-W-O film, etc.
  • metallic materials as Au, Pt, Ti, Al, etc.
  • various conductive polymer materials such as Au, Pt, Ti, Al, etc.
  • one or both of the source electrode and the drain electrode can be formed of an In-W-Zn-O film, an In-W-Sn-O film or an In-W-Sn-Zn-O film, like the channel layer 3.
  • the channel layer 3 as well as the source electrode 4 and the drain electrode 5 can be formed by use of the same film-forming apparatus, whereby a reduction in cost can be contrived.
  • transparency in the visible light region can be obtained, it becomes possible to cope with a wide range of applications.
  • the source electrode 4 and the drain electrode 5 are required of good conductivity; normally, these electrodes are controlled to have an electrical resistivity of 10 -5 to 10 -1 ⁇ cm, particularly 10 -5 to 10 -3 ⁇ cm.
  • the source electrode 4 and the drain electrode 5 are formed by forming an In 2 O 3 film, an ITO film, an In-Ti-O film, an In-W-O film, an In-W-Zn-O film, an In-W-Sn-O film, or an In-W-Sn-Zn-O film by the sputtering method like the channel layer 3, such a low resistivity can be attained by controlling the amount of oxygen introduced into the film in such a manner as to positively introduce oxygen deficiency into the film.
  • these electrodes 4 and 5 can also be conducted by adopting the dual cathode sputtering method or the PEM control, like in the case of the channel layer 3. In this case, stable control of the composition and the oxygen content of the thin film can be conducted, without depending on the state of the target; thus, a film-forming process with high reliability can be performed.
  • a compositionally gradient film in which the oxygen content of the film is gradually varied may be formed at the interfaces between the channel layer 3 and each of the source electrode 4 and the drain electrode 5. This ensures that the barrier at the interfaces between the channel layer 3 and each of the source electrode 4 and the drain electrode 5 is reduced, injection of carriers is facilitated, and enhancement of characteristics can be expected.
  • the substrate is not restricted to this one, and those conventionally known as substrates for electronic devices such as transistors can be used.
  • substrates for electronic devices such as transistors
  • transparent substrates e.g., glass substrates such as white sheet glass, blue sheet glass, quartz glass, etc.
  • PET polyethylene terephthalate
  • the Si substrate 1 is made to be a gate electrode and conduction with this gate electrode is secured through the silver paste in the TFT device of FIG. 1 above, an insulating substrate may be used and a gate electrode and a gate insulating film may be separately formed on the substrate.
  • the gate electrode can be formed by forming an In 2 O 3 film, an ITO film, an In-Ti-O film, an In-W-O film, an In-W-Zn-O film, an In-W-Sn-O film, or an In-W-Sn-Zn-O film by use of the same film-forming apparatus as that used at the time of forming the channel layer 3.
  • the electrical resistivity of the gate electrode can be set to be 10 -5 to 10 -1 ⁇ cm, particularly 10 -5 to 10 -3 ⁇ cm, like in the case of the source electrode 4 and the drain electrode 5.
  • the gate insulating film may be formed by a known method while using a known material such as metal oxides, e.g., SiO 2 , Y 2 O 3 , Ta 2 O 5 , Hf oxide, etc., or insulating polymer materials, e.g., polyimides.
  • the electrical resistivity of the gate insulating film may be normally 1 ⁇ 10 6 to 1 ⁇ 10 15 ⁇ cm, particularly 1 ⁇ 10 10 to 1 ⁇ 10 15 ⁇ cm.
  • the bipolar thin film transistor according to the second-named invention of the present invention is, for example, a TFT device as shown in FIG. 2 , wherein a channel layer 3 is formed of a stack including an organic material film 3b and an indium-containing metal oxide film 3a doped with at least one of tungsten, tin, and titanium.
  • an Si substrate (gate electrode) 1, a thermal oxide film (gate insulating film) 2, a source electrode 4, a drain electrode 5 and a silver paste 6 are the same as in the TFT device of FIG. 1 which has been shown as an example of the thin film transistor according to the first-named invention. Further, the layout configuration of these elements with the channel layer 3 is also the same as in the TFT device of FIG. 1 . Besides, in the bipolar thin film transistor according to the second-named invention, as above-mentioned, the channel layer 3 is formed of a stacked structure of the organic material film 3b and the metal oxide film 3a.
  • the metal oxide film 3a is formed to include indium doped with at least one of tungsten, tin, and titanium (InWO x , InSnO x , InTiO x ).
  • the metal oxide film 3a is formed to include indium doped with tungsten and at least one of tin, titanium, and zinc (InWSnO, InWTiO, InWZnO).
  • the use of such a material ensures that electrical resistivity can be comparatively easily controlled by controlling the degree of oxygen deficiency and the amount of doping with tungsten, at the time of forming the metal oxide film 3a.
  • IZO is used as the metal oxide film 3a like in the prior art, the conductivity of the film becomes too high, resulting in that at the time of stacking the organic material film 3b on the IZO of the metal oxide film 3a, the characteristic properties of the metal oxide film 3a located on the lower side would be changed greatly.
  • the resistivity By thus setting the resistivity to a somewhat higher value through controlling the amount of oxygen introduced and the amount of doping with tungsten, it is possible to ensure that the semiconductor characteristics of good characteristics of the metal oxide film 3a can be maintained, in other words, TFT characteristics can be maintained in good condition, after the organic material film 3b is formed on the metal oxide film 3a. Accordingly, it is possible to construct a bipolar thin film transistor which is capable of bipolar operations and which has both high performance and high reliability. In addition, when such a material as above-mentioned is used, a transparent conductive film can be obtained and, therefore, a transparent thin film transistor can be fabricated.
  • the conductivity of the metal oxide film can be controlled more effectively.
  • a heating step for adhesion to a panel, for sealing step or the like is always needed as a post-step in the process of completing the products. After the post-annealing (described later) as the heating step is carried out, the conductivity of the metal oxide film depends on only the amount of doping with tungsten.
  • the conductivity of IWO depends on both the amount of oxygen introduced and the amount of doping with tungsten.
  • the oxygen content of the metal oxide film comes to rest in a thermodynamically stable state, so that the conductivity comes to be independent from the amount of oxygen introduced at the time of film formation.
  • the conductivity of the film can be controlled by varying the amount of doping with tungsten.
  • the conductivity of the inorganic semiconductor material would become too strong after post-annealing, so that this material would be unable to function as a semiconductor.
  • the bipolar transistor of the organic-inorganic semiconductor structure of the present invention using the above-mentioned material as the inorganic semiconductor material, the conductivity of the inorganic semiconductor material would not become too strong even after post-annealing, so that this material can function as a semiconductor.
  • a heating step for adhesion to a panel, for sealing step or the like is always needed as a post-step in the process of completing the products. Therefore, when the above-mentioned material is used as the inorganic semiconductor material, it is possible to obtain a highly thermally stable transistor which can retain the function as semiconductor even in the case where a heating treatment such as post-annealing is conducted.
  • the resistivity of the metal oxide film 3a can be controlled more easily and more accurately. This ensures that before stacking the metal oxide film 3a as the channel layer, it is possible to form the metal oxide film 3a that has a desired resistance for offering good TFT characteristics.
  • InWO x , InWSnO, InWTiO, and InWZnO which contain tungsten, have the tendency to retain amorphousness and, hence, are excellent in thermal stability and film flatness properties.
  • the amount of tungsten contained in the metal oxide film 3a is preferably not less than 0.6 wt% and less than 15 wt%, based on the whole part of the metal oxide film. If the tungsten content reaches or exceeds 15 wt%, the resistivity would become too high to make the film insulating, so that it may be impossible to maintain good TFT characteristics.
  • the metal oxide film 3a of the channel layer 3 has an electrical resistivity that is normally controlled to 10 -1 to 10 5 ⁇ cm, particularly 1 to 10 4 ⁇ cm.
  • the above-mentioned InWO x , InSnO x , InTiO x , and further preferably InWSnO, InWTiO, and InWZnO permit the electrical resistivity to be comparatively easily controlled by controlling the degree of oxygen deficiency at the time of film formation.
  • the metal oxide film 3a for forming a part of the channel layer 3 specifically, the above-mentioned InWO x film, InSnO x film, InTiO x film, or further preferably InWSnO film, InWTiO film, or InWZnO film, there can be used physical vapor deposition methods such as a DC reactive sputtering method, an RF sputtering method, a pulse laser evaporation method, etc. like in the case of the first-named invention. Particularly, it is preferable to adopt a sputtering method conducted using an indium-containing target in an oxidizing gas-containing atmosphere.
  • the flow rate of oxygen gas it is possible to control the oxygen deficiency amount of the metal oxide film (InWO x film, InSnO x film, InTiO x film, InWSnO film, InWTiO film, InWZnO film). Therefore, even where the channel layer 3 is formed by stacking the organic material film 3b on the metal oxide film 3a, it is possible to prevent the characteristic properties of the metal oxide film 3a from being changed greatly. In other words, even where the organic material film 3b is further stacked on the metal oxide film 3a, the electrical resistivity of the metal oxide film 3a can be controlled to a resistivity suitable for the channel layer 3. Consequently, n-type and p-type bipolar operations can be driven in good conditions.
  • the metal oxide film InWO x film, InSnO x film, InTiO x film, InWSnO film, InWTiO film, InWZnO film.
  • an InW metal target and an InWO x ceramic target can be used in the case of forming the InWO x film
  • an InTi metal target and an InTiO x ceramic target can be used in the case of forming the InTiO x film
  • an InSn metal target and an InSnO x ceramic target can be used in the case of forming the InSnO x film.
  • the conventional film-forming method such as the DC reactive sputtering method and the RF sputtering method has a problem in that, due to comparatively low rate of film formation, it may be impossible to obtain sufficient productivity. It has another problem in that, since stable composition control for the InWO x film, InSnO x film, InTiO x film, InWSnO film, InWTiO film or InWZnO film is not easy to achieve, it may be difficult to maintain characteristics.
  • the dual cathode sputtering method may be applied so as to enhance productivity, like in the case of the first-named invention. Further, it is preferable to use a feedback system based on the above-mentioned PEM (Plasma Emission Monitor) control, whereby stable control of the composition and the oxygen content of the thin film can be performed independently from the state of the target.
  • PEM Pullasma Emission Monitor
  • the organic material layer 3b for forming a part of the channel layer 3 is formed of F8T2, P3HT, pentacene, or tetrabenzoporphyrin.
  • the material to be used is not limited to these materials, and the organic material film 3b may be formed of any of those general materials which are used as organic material semiconductor in transistors.
  • the method for forming the organic material film 3b constituting a part of the channel layer 3 is not specifically restricted, and the film may be formed by a known method. For instance, a spin coating method is used suitably.
  • the channel layer 3 configured by a stack of the metal oxide film 3a and the organic material film 3b is preferably formed by stacking the metal oxide film 3a and the organic material film 3b in this order from the gate electrode 1 side (the lower side in FIG. 2 ).
  • the metal oxide film 3a is formed particularly by a sputtering method; on the other hand, the organic material film 3b can be formed by vapor deposition, but is preferably formed particularly by a spin coating method, from the viewpoint of cost reduction.
  • the organic material film 3b may be altered (denatured) by exposure to plasma during the sputtering for forming the metal oxide film 3a; besides, a large amount of the organic material may be mixed into the metal oxide film 3a.
  • the channel layer 3 in the TFT device according to the third-named invention is not restricted to the stacked form having the metal oxide film 3a as the lower layer and the organic material film 3b as the upper layer as shown in FIG. 2 .
  • a stacked form can be adopted in which the organic material film 3b is the lower layer and the metal oxide film 3a is the upper layer.
  • the source electrode 4 and the drain electrode 5 are preferably formed in contact with the upper surface of the organic material film 3b. With both the electrodes thus formed on the organic material film 3b, there is obtained an effect such that contact resistance is greatly reduced, and good TFT characteristics can be obtained. Then, from this viewpoint, also, the channel layer 3 is preferably formed by stacking the metal oxide film 3a and the organic material film 3b in this order from the gate electrode 1 side (the lower side in FIG. 2 ).
  • the source electrode 4 and the drain electrode 5 can be formed from the same material and in the same manner as in the case of the above-described first-named invention.
  • InWO x , InSnO x , InTiO x , InZnO x , InWSnO, InWTiO, InWZnO, etc. like the metal oxide film 3a of the channel layer 3.
  • the conductivities of the source electrode 4 and the drain electrode 5 are also controlled to an electrical resistivity of normally 10 -5 to 10 -1 ⁇ cm, particularly 10 -5 to 10 -2 ⁇ cm, like in the case of the above-described first-named invention.
  • the electrodes can be formed by a sputtering method, like in the case of forming the metal oxide film 3a constituting a part of the channel layer 3.
  • the substrate 1, the thermal oxide film 2, the silver paste 6 and the like are the same as in the first-named invention described above, so that the same reference symbols as in FIG. 1 are used in FIG. 2 , and descriptions of these elements are omitted.
  • the thin film transistors according to the first-named invention and the second-named invention are not restricted to the bottom-gate top-contact type ones shown in FIGS. 1 and 2 , respectively.
  • the thin film transistors may take other forms, such as bottom-gate bottom-contact type, top-gate bottom-contact type, top-gate top-contact type, etc.
  • the method for manufacturing a thin film transistor according to the third-named invention includes forming on a substrate an indium-containing metal oxide film by sputtering so that one or more elements including at least a channel layer or a part of the channel layer, of elements of the channel layer, a source electrode, a drain electrode and a gate electrode, are formed from the indium-containing metal oxide film, and conducting a heat treatment after formation of these elements.
  • the thin film transistor to be manufactured in the present invention is not specifically restricted.
  • Examples of the thin film transistor include the thin film transistor of the first-named invention that is shown in FIG. 1 , and the bipolar thin film transistor of the second-named invention that is shown in FIG. 2 .
  • the channel layer 3 ( FIG. 1 ) or the metal oxide film 3a ( FIG. 2 ) of the channel layer 3 is formed on the substrate 1 by forming the indium-containing metal oxide film by the above-mentioned sputtering method, further, the source electrode 4 and the drain electrode 5 and, further, depending on the TFT structure, the above-mentioned gate electrode, are formed to thereby form the elements of the TFT device, and thereafter the heat treatment is conducted.
  • the heating temperature in conducting the heat treatment is appropriately set according to the kind, size, thickness, etc. of the metal oxide film for forming the channel 3 ( FIG. 1 ) or the metal oxide film layer 3a ( FIG. 2 ) constituting a part of the channel layer 3, and is not particularly limited; normally, the heating temperature may be 150 to 300°C, particularly 150 to 200°C.
  • the treatment time may be 10 to 120 minutes, particularly 30 to 60 minutes.
  • the atmosphere for the heating treatment the atmospheric air may be adopted without any problem.
  • the present invention by conducting the heat treatment, particularly by applying the heat treatment to the In-W-Zn-0 film, the following three effects can be obtained. Firstly, even in the case where the amount of oxygen introduced at the time of film formation by sputtering is not an optimum value and satisfactory TFT characteristics cannot necessarily be obtained, the TFT characteristics can be brought into an optimal state by the heat treatment. Therefore, it becomes unnecessary to subtly control the quantity of oxygen introduced, attendant on the progress of erosion of the sputtering target. In addition, variations in TFT characteristics which might arise from the degree of vacuum reached during film formation by sputtering are eliminated, so that a TFT device with stable characteristics can be easily manufactured.
  • TFT characteristics such as threshold voltage and mobility can be easily controlled.
  • a 10 mm ⁇ 10 mm specimen was formed by cutting.
  • a shadow mask was adhered to the specimen so as to hide a central portion of the specimen, and ohmic electrodes composed of a 30 nm-thick ITO film were formed on the four corners of the specimen by a DC magnetron sputtering process, to obtain Sample 1.
  • the sputtering conditions were as follows.
  • a 30 nm-thick In-W-Zn-O film was formed as a channel layer by a DC magnetron sputtering process.
  • the sputtering conditions were set to be the same as in forming the In-W-Zn-O film of Sample 1 above, and the sputtering was conducted without heating the substrate.
  • a 30 nm-thick ITO film was formed as a source electrode and a drain electrode by a DC magnetron sputtering process, to fabricate a thin film transistor (TFT device) configured as shown in FIG. 1 .
  • the sputtering conditions were set to be the same as in forming the ohmic electrodes of Sample 1 above.
  • patterning was conducted using a shadow mask so as to obtain a channel length of 0.1 mm and a channel width of 6.4 mm.
  • a 30 nm-thick In-W-Sn-O film was formed as a channel layer by a DC magnetron sputtering process.
  • the sputtering conditions were set to be the same as in forming the In-W-Sn-O film of Sample 2 above, and the sputtering was carried out without heating the substrate.
  • a 30 nm-thick ITO film was formed as a source electrode and a drain electrode by a DC magnetron sputtering process, to fabricate a thin film transistor (TFT device) configured as shown in FIG. 1 .
  • the sputtering conditions were set to be the same as in forming the ohmic electrodes of Sample 2 above.
  • pattering was performed using a shadow mask in the same manner as in Example 1 above, so as to obtain a channel length of 0.1 mm and a channel width of 6.4 mm.
  • a 30 nm-thick In-W-Sn--Zn-O film was formed as a channel layer by a DC magnetron sputtering process.
  • the sputtering conditions were set to be the same as in forming the In-W-Sn-Zn-O film of Sample 3 above, and the sputtering was conducted without heating the substrate.
  • a 30 nm-thick ITO film was formed as a source electrode and a drain electrode by a DC magnetron sputtering process, to fabricate a thin film transistor (TFT device) configured as shown in FIG. 1 .
  • the sputtering conditions were set to be the same as in forming the ohmic electrodes of Sample 3 above.
  • patterning was conducted using a shadow mask in the same manner as in Example 1 above, so as to obtain a channel length of 0.1 mm and a channel width of 6.4 mm.
  • a 30 nm-thick In-W-O film was formed as a channel layer by a DC magnetron sputtering process.
  • the sputtering conditions were set to be the same as in forming the In-W-O film of Sample 4 above, and the sputtering was carried out without heating the substrate.
  • a 30 nm--thick ITO film was formed as a source electrode and a drain electrode by a DC magnetron sputtering process, to fabricate a thin film transistor (TFT device) configured as shown in FIG. 1 .
  • the sputtering conditions were set to be the same as in forming the ohmic electrodes of Sample 4 above.
  • patterning was performed using a shadow mask in the same manner as in Example 1 above, so as to obtain a channel length of 0.1 mm and a channel width of 6.4 mm.
  • TFT characteristics were evaluated using a semiconductor parameter analyzer "4155C" made by Agilent Technologies.
  • the drain voltage was 70 V
  • the gate electrode was swept over the range of -70 to +70 V.
  • field effect mobility ⁇ FE was calculated. The results are shown in Table 2.
  • Example 1 In-W-Zn-O 3.23 1.1 ⁇ 10 3 +3.3
  • Example 2 In-W-Sn-O 7.19 5.4 ⁇ 10 7 -7.1
  • Example 3 In-W-Sn-Zn-O 5.63 7.5 ⁇ 10 7 -3.7 Comparative Example 1 In-W-O 1.36 1.2 ⁇ 10 8 +5.4
  • the thin film transistors (Examples 1 to 3) pertaining to the first-named invention of the present invention wherein the channel layer is composed of the In-W-Zn-O film, the In-W-Sn-O film or the In-W-Sn-Zn-O film obtained by doping the In-W-O film further with Zn and/or Sn show a largely enhanced field effect mobility, as compared with the thin film transistor (Comparative Example 1) wherein the In-W-O film is used as the channel layer.
  • Example 2 In the same manner as in Example 1, a 30 nm-thick In-W-Zn-O film was formed on a silicon wafer as a channel layer. In this instance, the quantity of oxygen introduced during film formation was varied as follows, to form five kinds of In-W-Zn-O films.
  • a 30 nm-thick ITO film was formed as a source electrode and a drain electrode in the same manner as in Example 1, so as to fabricate thin film transistors (TFT devices) configured as shown in FIG. 1 .
  • the thin film transistors were heat treated in air at 150°C for 30 min, to fabricate five kinds of thin film transistors.
  • Example 4 For the thin film transistors obtained respectively in Example 4 and Comparative Example 2 above, TFT characteristics were evaluated using a semiconductor parameter analyzer "4155C" made by Agilent Technologies. The results for the thin film transistor of Example 4 above are represented by the graph in FIG. 3 , while the results for the thin film transistor of Comparative Example 2 are represented by the graph in FIG. 4 .
  • the thin film transistor of Example 4 above and the thin film transistor of Comparative Example 2 above are compared with each other in regard of transfer characteristic.
  • the transfer characteristic of the thin film transistor of Comparative Example 2 which was manufactured by the method without any heat treatment varies greatly depending on the quantity of oxygen introduced during formation of the In-W-Zn-O film.
  • the transfer characteristic of the thin film transistor of Example 4 which was manufactured with the final heat treatment is little affected by variations in the quantity of oxygen introduced during formation of the In-W-Zn-O film; thus, it is recognized that TFT characteristics are little dependent on variations in the quantity of oxygen introduced during the film formation.
  • the thin film transistors fabricated respectively in Example 4 and Comparative Example 2 above, by setting the quantity of oxygen introduced during formation of the In-W-Zn-O film so that Ar/O 2 94/6.0 sccm, were each put to successive 100 runs of measurement of transfer characteristic in the same manner as in Experiment 1, and comparison was made in regard of the measurement results obtained respectively at the 1st, 10th and 100th runs of measurement.
  • the results for the thin film transistor of Example 4 are represented by the graph in FIG. 5
  • the results for the thin film transistor of Comparative Example 2 are represented by the graph in FIG. 6 .
  • the transfer characteristic of the thin film transistor obtained by the method of Example 4 showed little shift in threshold voltage even when the measurement was repeated 100 times ( FIG. 5 ).
  • the transfer characteristic of the thin film transistor obtained by the method of Comparative Example 2 showed a large shift, toward the minus side, in threshold voltage as the measurement was repeated.
  • a channel layer composed of an In-W-Zn-O film was formed on a silicon wafer in the same manner as in Example 1, under the following sputtering conditions.
  • the target composed of a sintered body of In-W-Zn-O four kinds of targets differing in W content as indicated by the following sputtering conditions were used, to form four kinds of In-W-Zn-O films.
  • a source electrode and a drain electrode composed of an ITO film were formed in the same manner as in Example 1, followed by a heat treatment in air at 150°C for 30 min in the same manner as in Example 1, to fabricate four kinds of thin film transistors.
  • measurement of transfer characteristic was conducted to evaluate TFT characteristics, in the same manner as in Experiment 1 above. The results are represented by the graph in FIG. 7 .
  • TFT characteristics vary continuously with W content of the sintered body of In-W-Zn-O used as the target. It is recognized in this case that the threshold voltage is shifted toward the plus side as the W content increases, showing that the quantity of carriers in the semiconductor film (channel layer) depends on the W content of the target.
  • TFT characteristics can be easily controlled by regulating the W content of the target in forming the In-W-Zn-O film.
  • a 30 nm-thick film of InWO oxide semiconductor was formed on a silicon wafer formed on its surface with a thermal oxide film (SiO 2 ) as a gate insulating film.
  • the film formation was conducted by a sputtering method under the following conditions.
  • source/drain electrodes having a stack of 3 nm-thick Cr and 45 nm-thick Au were formed by a sputtering method. Patterning was conducted by a known method using a shadow mask. Besides, the channel length was set to 0.1 mm, and the channel width was set to 6.4 mm.
  • TFT device bipolar thin film transistor
  • a 30 nm-thick film of InWO oxide semiconductor was formed on a silicon wafer formed on its surface with a thermal oxide film (SiO 2 ) as a gate insulating film.
  • a film of a p-type organic semiconductor was formed on the thus formed InWO film by a vapor deposition method.
  • the vapor deposition conditions were as follows.
  • TFT device bipolar thin film transistor
  • a 30 nm-thick film of InZnO oxide semiconductor was formed on a silicone wafer formed on its surface with a thermal oxide film (SiO 2 ) as a gate insulating film.
  • InZnO film was coated with a p-type organic semiconductor.
  • the coating was conducted by spin coating under the following conditions. ⁇ Spin Coating Conditions> Organic semiconductor used: F8T2 Solvent: chloroform Solvent concentration: 2 mg/ml Spinner rotating speed: 1000 rpm Rotation time: 10 seconds Drying conditions: 60°C ⁇ 10 minutes
  • TFT device In the same manner as in Example 6, source/drain electrodes were formed and, thereafter, a heat treatment was conducted, to obtain a bipolar thin film transistor (TFT device).
  • a 30 nm-thick film of InZnO oxide semiconductor was formed on a silicon wafer formed on its surface with a thermal oxide film (SiO 2 as a gate insulating film.
  • a film of a p-type organic semiconductor was formed on the thus formed InZnO film by a vapor deposition method.
  • the vapor deposition conditions were as follows. ⁇ Vapor Deposition Conditions> Organic semiconductor used: pentacene Degree of vacuum reached: below 1 ⁇ 10 -4 Pa Film thickness: about 50 nm
  • TFT device In the same manner as in Example 6, source/drain electrodes were fabricated and, thereafter, a heat treatment was conducted, to obtain a bipolar thin film transistor (TFT device).
  • FIG. 8 shows the evaluation results of TFT characteristics.
  • the results of the TFT characteristic evaluation experiment show that in Example 6, holes accumulated in the p-type organic semiconductor flowed as carriers and hence a p-type operation was exhibited when the gate voltage was in the range of -200 V to -110 V. Besides, when the gate voltage was in the range of -90 V to 50 V, electrons accumulated in the n-type oxide semiconductor layer composed of the InWO film flowed as carriers and hence an n-type operation was exhibited. The range from -110 V to -90 V corresponds to an OFF state.
  • both n-type and p-type polar operations can be realized by forming an InWO film as the n-type oxide semiconductor.
  • Example 7 also, substantially the same results were exhibited. Specifically, it was confirmed that in the TFT device wherein a multilayer film having both an n-type oxide semiconductor and pentacene, which is a p-type organic semiconductor, is used to form the channel, both n-type and p-type polar operations can be realized by forming an InWO film as the n-type oxide semiconductor.
  • Example 6 In forming the film of the InWO oxide semiconductor in Example 6, the film formation was conducted by varying the amount of doping with tungsten. In the same manner as in Example 6, a 30 nm-thick film of InWO oxide semiconductor was formed on a silicon wafer formed on its surface with a thermal oxide film (SiO 2 ) as a gate insulating film. In the same manner as in Example 6 except for the difference in tungsten content, the film formation was conducted by a sputtering method under the following conditions.
  • the InWO film thus formed was spin coated with a p-type organic semiconductor in the same manner as in Example 6. Further, in the same manner as in Example 6, source/drain electrodes were fabricated and, thereafter, a heat treatment was conducted, to obtain a bipolar thin film transistor (TFT device).
  • TFT device bipolar thin film transistor
  • FIG. 9 shows evaluation results of TFT characteristics obtained in Example 6 ( ⁇ ) and Example 8 ( ⁇ , ⁇ ).
  • Example 6 in forming the film of the InWO oxide semiconductor of Example 6, the film formation was conducted by varying the amount of doping with tungsten, and the relationships of the amount of doping with tungsten with electrical resistivity of the InWO thin film, and with the characteristics of the bipolar transistor of the present invention, were examined.
  • FIG. 10 shows the relationship between the amount of doping with tungsten and electrical resistivity of the InWO thin film.
  • InWO films varied in the amount of doping with tungsten were each formed on a quarts glass under the following sputtering conditions, which are the same as in Example 6.
  • the films thus obtained were heat treated in air at 150°C, for annealing, and were subjected to measurement of resistivity by use of a Hall measurement system ResiTest 8300 made by Toyo Corp.
  • a Hall measurement system ResiTest 8300 made by Toyo Corp.
  • FIG. 10 good semiconductor-like resistivity was obtained when the amount of doping with tungsten was not less than 0.5 wt% and less than 15 wt%. It is seen that in the films doped with not less than 15 wt% of tungsten, the resistivity is not less than 10 5 ⁇ m, indicating that the insulating property is so high that the films are unsuitable as a semiconductor film for use in TFT. Also, it is clear that the films not containing tungsten at all are too high in conductivity.
  • these InWO films were each formed on a silicon wafer provided thereon with a thermal oxide film, in the same manner as in Examples 6 and 8, to fabricate bipolar transistors.
  • the spin coating conditions, the fabrication of source/drain electrodes, and annealing were the same as in Example 6.
  • TFT devices fabricated evaluation of TFT characteristics was conducted by using a semiconductor parameter analyzer 4155C made by Agilent Technologies and by sweeping the gate voltage over the range of -200 V to +50 V while applying a drain voltage of +50 V.
  • FIG. 11 is a diagram in which the ON/OFF ratio obtained by comparing the current in an OFF state with the current in an ON state when the gate voltage is +50 V is plotted as dependency on the amount of doping with tungsten, based on the results obtained above.
  • a sufficient ON/OFF ratio can be obtained in the case where the amount of doping with tungsten is not less than 0.5 wt% and less than 15 wt%.
  • the InWO film became a perfect conductor, and the TFT device was always in the ON state, so that the ON/OFF ratio was 1.
  • the amount of doping with tungsten was not less than 15 wt%, the resistivity of InWO was too high, so that the TFT device was always in the OFF state, and it was almost impossible to obtain a substantial ON/OFF ratio.

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EP10764534A 2009-04-17 2010-04-16 Transistor à film mince et son procédé de fabrication Withdrawn EP2421048A4 (fr)

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JP2009101020A JP2010251606A (ja) 2009-04-17 2009-04-17 薄膜トランジスタ
JP2009101005A JP2010251604A (ja) 2009-04-17 2009-04-17 薄膜トランジスタの製造方法
JP2009130965A JP2010278336A (ja) 2009-05-29 2009-05-29 バイポーラ型薄膜トランジスタ
PCT/JP2010/056850 WO2010119952A1 (fr) 2009-04-17 2010-04-16 Transistor à film mince et son procédé de fabrication

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EP3061735A4 (fr) * 2014-10-22 2016-12-14 Sumitomo Electric Industries Oxyde fritté et dispositif à semi-conducteur
US20170069474A1 (en) 2015-02-13 2017-03-09 Sumitomo Electric Industries, Ltd. Oxide sintered body and method for manufacturing the same, sputtering target, and semiconductor device
US9957604B2 (en) 2014-03-25 2018-05-01 Sumitomo Electric Industries, Ltd. Oxide sintered body and method for manufacturing the same, sputtering target, and semiconductor device

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JP5723262B2 (ja) * 2010-12-02 2015-05-27 株式会社神戸製鋼所 薄膜トランジスタおよびスパッタリングターゲット
CN103268918B (zh) * 2012-06-29 2016-06-29 上海天马微电子有限公司 双极性薄膜晶体管及其制造方法
JP5966840B2 (ja) 2012-10-11 2016-08-10 住友金属鉱山株式会社 酸化物半導体薄膜および薄膜トランジスタ
JP6107085B2 (ja) 2012-11-22 2017-04-05 住友金属鉱山株式会社 酸化物半導体薄膜および薄膜トランジスタ
KR102090289B1 (ko) 2013-05-30 2020-04-16 삼성디스플레이 주식회사 산화물 스퍼터링 타겟, 이를 이용한 박막 트랜지스터 및 그 제조 방법
KR102216538B1 (ko) * 2013-10-23 2021-02-18 삼성전자주식회사 트랜지스터 및 그 동작 방법
CN103659106A (zh) * 2013-11-13 2014-03-26 中天建设集团有限公司 一种木模板支架钢板电焊方法
CN105745183B (zh) * 2014-08-12 2018-03-13 住友电气工业株式会社 氧化物烧结体及其制造方法、溅射靶、以及半导体器件
JP6501385B2 (ja) * 2014-10-22 2019-04-17 日本放送協会 薄膜トランジスタおよびその製造方法
WO2016121152A1 (fr) * 2015-01-26 2016-08-04 住友電気工業株式会社 Film d'oxyde semi-conducteur et dispositif à semi-conducteur
CN108011041B (zh) * 2016-10-28 2020-03-10 京东方科技集团股份有限公司 半导体薄膜和薄膜晶体管、其制作方法、相关装置
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9957604B2 (en) 2014-03-25 2018-05-01 Sumitomo Electric Industries, Ltd. Oxide sintered body and method for manufacturing the same, sputtering target, and semiconductor device
US10480060B2 (en) 2014-03-25 2019-11-19 Sumitomo Electric Industries, Ltd. Oxide sintered body and method for manufacturing the same, sputtering target, and semiconductor device
EP3061735A4 (fr) * 2014-10-22 2016-12-14 Sumitomo Electric Industries Oxyde fritté et dispositif à semi-conducteur
US10087517B2 (en) 2014-10-22 2018-10-02 Sumitomo Electric Industries, Ltd. Oxide sintered body and semiconductor device
US20170069474A1 (en) 2015-02-13 2017-03-09 Sumitomo Electric Industries, Ltd. Oxide sintered body and method for manufacturing the same, sputtering target, and semiconductor device
US10475631B2 (en) 2015-02-13 2019-11-12 Sumitomo Electric Industries, Ltd. Oxide sintered body and method for manufacturing the same, sputtering target, and semiconductor device
US10811238B2 (en) 2015-02-13 2020-10-20 Sumitomo Electric Industries, Ltd. Oxide sintered body and method for manufacturing the same, sputtering target, and semiconductor device

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EP2421048A4 (fr) 2012-08-29
WO2010119952A1 (fr) 2010-10-21
KR20120004526A (ko) 2012-01-12
CN102460712A (zh) 2012-05-16
US20120037897A1 (en) 2012-02-16

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